The objective of the Collaborative Longitudinal Evaluation of Keratoconus(CLEK) Study is to characterize the progression of keratoconus over a broad spectrum of disease severity. The study will include patients ages 12 through 65 inclusive with evidence of corneal irregularity in at least one eye and either Fleishers ring; Vogt's striae or corneal scarring in at least one eye. Progression of keratoconus will be measured by changes in corneal curvature (keratometry), visual acuity (high and low contrast Bailey-Lovie), visual quality of life (Javitt Visual Function Questionnaire), incidence of central corneal scarring, and contact lens required for definite apical clearance. Thirteen clinics will participate in recruiting and following a total of 1000 patients with keratoconus. Patients will be examined annually for the study for a minimum of 3 years. Resource enters for the study include the Study Chairman's office at the University of California-Berkeley, Photography Reading Center at Ohio State University, and the Data Coordinating Center at Washington University Medical School in St. Louis. The DCC is responsible for the conduct of the study in collaboration with the Executive Committee, Steering Committee, Policy Advisory Board and representatives of the National Eye Institute. The DCC is responsible for the study design, management of study data, monitoring the performance of the Reading Center and participating clinics, preparation of performance reports, analysis of data and presentation of results.